## Facts

- Purchasers of Honda Gold Wing GL1800 motorcycles alleged a common steering “wobble” design defect causing excessive side-to-side oscillation of the front steering assembly.
- Plaintiffs sought class certification under Federal Rule of Civil Procedure 23(b)(3), contending common issues predominated because the defect was uniform across the class.
- Plaintiffs relied primarily on an engineering expert, Mark Ezra, who proposed a “wobble decay” standard based on assumed human reaction time and opined that oscillations should decay to 37% of initial amplitude within 0.75 seconds.
- Ezra conducted tests purporting to show the GL1800 failed his wobble-decay standard, supporting a class-wide defect theory.
- Honda challenged Ezra’s methodology under Daubert, arguing the testimony was unreliable and inadmissible and that, without it, plaintiffs could not prove Rule 23(b)(3) predominance.
- The district court expressed concerns about Ezra’s methodology but did not make a definitive Daubert ruling at the certification stage; it effectively accepted the testimony with reservations and certified the class.
- Honda obtained interlocutory review of the certification order under Rule 23(f).

## Issues

1. Whether a district court must make a definitive Daubert admissibility ruling on expert testimony at the class-certification stage when that testimony is critical to satisfying Rule 23(b)(3).
2. Whether plaintiffs can establish Rule 23(b)(3) predominance when their central expert proof is inadmissible under Daubert.

## Decision

- The Seventh Circuit reversed the class-certification order.
- The court held that when expert testimony is critical to the Rule 23 analysis, the district court must conduct a full Daubert inquiry and conclusively rule on admissibility before certifying a class.
- Applying Daubert, the court found Ezra’s opinions inadmissible because his wobble-decay standard and testing lacked indicia of reliability (including insufficient testing, peer review, acceptance, and controls) and did not reliably isolate a common design defect from other potential causes.
- Without admissible expert evidence establishing a common defect, plaintiffs failed to show that common questions predominated under Rule 23(b)(3).

## Legal Principles

- Class certification requires a rigorous analysis of Rule 23 requirements; that analysis may overlap with merits-related evidentiary questions when necessary to decide certification.
- If expert testimony is essential to establishing Rule 23(b)(3) predominance or other certification requirements, the court must resolve Daubert admissibility at the certification stage and may not defer the ruling or admit the testimony conditionally.
- Unreliable expert methodology that is not shown to be scientifically valid under Daubert cannot supply the proof needed to establish class-wide defect and predominance.

## Conclusion

The Seventh Circuit required district courts to decide Daubert admissibility at class certification when expert testimony is central to Rule 23(b)(3), and it reversed certification because the plaintiffs’ key expert evidence was inadmissible and could not establish predominance.


Am. Honda Motor Co. v. Allen, 600 F.3d 813 (7th Cir. 2010)